Study And Implementation Of Resonant Circuit For Power Supply For High-power-temperature Electromagnetic Acoustic Transducer Excitation

Electromagnetic ultrasonic testing is widely used in the on-line nondestructive testing and evaluation of high temperature metal samples.Compared to the traditional piezoelectric ultrasonic Transducer,electromagnetic acoustic transducer(EMAT)has become hot off the press of nondestructive testing that uses noncontact,high-temperature-resistance and high-speed mobile metal samples.The impedance of EMAT is impact on properties of the test material,the skin effect,proximity effect and high temperature of the coil lifting distance and high frequency excitation and high temperature and so on other factors;the impedance mismatch causes the electromagnetic ultrasonic power supply excitation to absorb the high reflected power and even burn the power supply.In view of this problem,this paper presents a design method of resonant EMAT power supply excitation.Through theoretical modeling and simulation analysis,based on the EMAT equivalent circuit model,the double resonance enhancement output voltage gain is realized,and the sensitivity variation of resonance parameters is analyzed by Monte Carlo analysis method.The results for the development of high temperature EMAT power supply excitation and detection system to provide theoretical guidance and building the foundation.In this paper,the mechanism of electromagnetic ultrasonic detection is studied and EMAT’s mathematical model is established,and the impedance characteristics of EMAT are modeling analyzed.The multi-field coupling control model is established and the model is validated based on the finite element simulation analysis.Transducer in the magnetic flux density under different excitation duration,eddy current field,Lorentz force and the change of ultrasonic stress field,by analyzing the distribution of several coupling characteristics of EMAT simplified equivalent circuit model,building the foundation for the research of the resonant EMAT circuit.Secondly,the model of resonant EMAT topology model is established and the steady-state analysis is carried out.The time domain/frequency domain analysis is carried out according to the resonant topology proposed in this paper,and the MATLAB/Simulink simulation model is established for verification.In order to optimize the parameter design method and sensitivity analysis of resonant circuit voltage/current,based on the Monte Carlo method,and using Pspice software that uses 400 sampling points in the statistical analysis of results.Finally,the optimal design principle of high temperature resonant exciter is obtained.In the process of the study,the phenomenon of resonance tailing is suppressed by improving the resonance topology.The improved resonant electromagnetic ultrasonic power supply excitation outputs the quasi-sinusoidal pulse and effectively restrains the high-order harmonic interference,which provides a basis for the realization of nonlinear EMAT detection.Additionally,the high temperature resonant EMAT power supply excitation is developed by designing the whole bridge inverter,driving circuit,buffer protection circuit and software design;the experimental platform was established to verify the duration,output power and efficiency of different pulses,and experimental results show that this method can achieve the voltage gain of nearly 16 times and the efficiency can reach over 90%,which proves the validity of this method that has good practicability.